1. Field
The disclosure relates generally to a public addressing (PA) system. In particular, this disclosure relates to using personal communication devices (PCDs) as microphones for a PA system.
2. Background
The addition of processing power, media processing capabilities, and high-bandwidth radio technologies to PCDs offers possibilities to develop novel solutions that may better user experience and improve productivity for various fields. In particular, the PCDs may be used to improve a PA system.
For example, hosts and attendees of a conference or seminar require access to the PA system for giving lecture, providing input, asking questions, and making comments. Typically, a microphone is passed or delivered to a user to allow the user access to the PA system. The passing and delivering of the microphone create inconvenience to the hosts/attendees, and a considerable amount of time is consumed in the process. To avoid the passing and the delivering of the microphones, PCDs (e.g., mobile phones) may be implemented to interface with the PA system such that the PCDs may act as microphones. Given that almost everyone has a PCD, the user may simply use his or her own PCD as a microphone when the user desires to access the PA system.
However, a drawback for using the PCDs as microphones is that feedback may occur. Feedback (also known as howling) occurs when a sound that has been captured, amplified, and broadcasted by the PA system is recaptured by the microphone of the PCD and amplified/broadcasted again. In this manner, a loop is created such that the sound is continuously being re-amplified over a short period of time. Such loops produce, with the speakers of the PA system, a high-pitched (howling) sound that is extremely unpleasant to the ears. Conventional PA systems are not capable of supporting sophisticated howling suppression techniques. Therefore, PCDs with sensitive microphones usually create feedback when used as microphones to the PA systems.
Moreover, feedback is especially likely to occur if audio signals (from multiple PCDs) having different amplitude ranges are fed into the input of the PA system. Although the conventional PA systems may be capable of suppressing feedback for a first amplitude range, such systems may not be capable of suppressing feedback for a second amplitude range which is greater than the first amplitude range. Thus, the conventional PA systems may not support feedback suppression for PCDs that output audio signals to the PA systems at different amplitude ranges.
One factor contributing to audio signals having different amplitude ranges is that PCDs may include hardware (e.g., microphones) with different performance characteristics. This is because the PCDs may be made by different manufacturers. Even different models from the same manufacturer may contain hardware from different component suppliers, such that the hardware may have different performance characteristics.
Another factor is that the speaking habits of the users may be different. For example, some may speak loudly (or keep the PCD close) while others may speak softly (or keep PCD far). Yet another factor is that different speakers of the PA system may have different performance characteristics related to outputting sound. Some other factors include, but are not limited to, the user's distance from the speakers, the microphone's frequency response, the sensitivity of the microphone, the direction of the microphone relative to the user, the acoustics of the room, the direction of the speaker with respect to user's location, and/or the like.